@mixin transition($direction) {
  transition: $direction linear .5s;
  -webkit-transition: $direction linear .5s;
  -o-transition: $direction linear .5s;
  -ms-transition: $direction linear .5s;
}

@mixin center() {
  display: -webkit-flex;
  -webkit-justify-content: center;
  -webkit-align-items: center;
}
